Does Dietary Menthol (0.5%) Increase Energy Expenditure and Facilitate Maintenance of Weight Loss Following Caloric Restriction? A Pilot Study

Excessive weight gain, otherwise known as obesity, has become a pervasive medical condition throughout the world. Though caloric restriction (CR) results in weight reduction, this weight loss is often unsustainable in the long term. As such, the goal is to find a treatment that can maintain the results of restricted energy intake (EI). Studies have found that dietary menthol could be a possible treatment and preventative measure for excessive weight gain. While several studies have found that, as an agonist of TRPM8, dietary menthol increases the energy expenditure (EE) of the body without impacting EI, they have not studied the efficacy of dietary menthol in preventing weight regain (WR) following a period of CR. Methods used in this experiment include studying young Sprague-Dawley rats during 24-hour periods towards the end of the following three phases: (1) an experimental phase of 12 weeks, comprised of ad-libitum feeding of high fat diet (HFD) to 10 rats and chow diet to 4 rats, (2) a CR phase of 4-weeks with controlled feeding of the HFD rats with either a chow diet (n=4) or chow diet + 0.5% dietary menthol (n=6) and keeping the other rats on chow (n=4), and (3) a WR period of 4-weeks with ad libitum feeding of the same diets as in CR. EI and EE (via indirect calorimetry) were measured over 24-hour periods and were divided by the rat’s respective body weight (BW) on testing day to normalize the sample population. The energy gap (EG) was determined by subtracting EE from EI. The experimental and WR phase revealed a positive EG or energy balance (EI > EE) whereas CR yielded a negative EG or energy balance (EI